In a suspension apparatus of a vehicle, for example, an upper link and a lower link are controlled to protrude or to retract by an actuator, thereby restraining variations in camber angle and tread of a wheel caused by bumping and rebounding in order to enhance steering stability performance (see, e.g., JP 6-047388 B2). The actuator includes a motor and a feed screw mechanism in which a male screw member is relatively rotated with respect to a female screw member by the motor.
In order to provide the right and left actuators with same operation characteristics, when a right screw is used in the feed screw mechanism of the right side actuator for example, it is necessary to use a left screw in the feed screw mechanism of the left side actuator. In other words, the right side actuator and the left side actuator need to be mirror symmetric with respect to a center plane of a vehicle body. Therefore, the right side actuator cannot be used as the left side actuator, and vice versa.
The housings for the right side actuator and the left side actuator are unlikely to be confused with each other, because the housings can be visually seen from outside. However, as for the components that are incorporated inside the housings, e.g., the output rods, the left side output rod might be accidentally assembled to the right side housing, and vice versa.